The above description applies to centripetal flow through the flow channels within the rotor, as long as the exit openings are located radially closer to the axis of rotation than the intake openings. In the case of power generating and powered working machines it is also possible, however, to provide centrifugal flow of the working medium within the rotor. In this case the intake openings are located radially closer to the axis of rotation than the exit openings. This embodiment is also included by the invention.
Known from U.S. Pat. No. 4,029,431 (DE-OS No. 24 40 475) is a fluid-flow machine of the type referred to in the introduction, wherein the elbows of the flow channels are directed such that the axial components of the relative velocity at the intake and exit openings extend in the same direction, while the tangential components are directed opposite to one another. This known fluid-flow machine is particularly adapted for use as a power generating or powered working machine designed for small high-speed values, i.e for small flow-through volumes in relation to the pressure drop per stage. That is because high tangential deflection of the flow within the rotor result in low relative velocities permitting low-loss flow-through also of smaller flow volumes as well as relatively high pressure drop per stage with sufficiently high circumferential speeds and absolute speeds at the inlet, or outlet, respectively.
A further advantageous employ of this construction lies in the field of the compression, or expansion, respectivels of gaseous mixtures with or without liquid components in technological processes requiring flow components to be introduced or withdrawn in the course of phase transformation. This is because such admixture processes, or separation processes, respectively, are greatly promoted by the secondary flows developing in the curved sections of the flow channels due to centrifugal forces. In these technological processes it is sometimes desirable to reduce not only the volume flow, but also the pressure drop per stage, in order to achieve optimum graduation of the phase transformation. Such reduction of the pressure drop per stage may of course be obtained by a reduction of the circumferential and absolute speeds at the inlet, or outlet, respectively, such reduction requiring, however, a machine of greater dimensions for a given performance, and thus, an increase in space requirements and material expenditure, and a lengthening of the flow paths within the rotor.
It is thus an object of the invention to achieve such reduction of the pressure drop per stage without reducing the circumferential and absolute speeds for combining a low volume flow with a relatively low pressure drop per stage and to increase the rotational speed capability of the machine in this manner.
In order to attain this object the invention provides that the leg of the radially outer deflector elbow leading towards the intake opening and the leg of the radially inner deflector elbow leading towards the exit opening are directed such that the tangential components of the relative velocity at the intake and exit openings are unidirectional or that these tangential components are completely absent at the intake openings or at the exit openings.
In accordance with the invention, it is not only a case of causing a working medium to flow through the fluid-flow machine, irrespective of whether it is employed as a powered working machine or a power generating machine, the invention also permitting to influence the physical and/or chemical properties of the working medium.
The effect of such influence may be enhanced according to the invention by adding and withdrawing flow components not outside of the machine, but rather in the elbows of the flow channels themselves. To this effect, an opening may be provided in a per se known manner (cf. periodical "Energie," Vol. 28 No. 6/7, 1976, p. 171 et seq.) at the outer periphery of the radially outer or inner elbow of each flow channel of any one rotor or guide wheel stage, respectively, such openings serving for separating flow components from the main flow or adding such flow components thereto via auxiliary channels in the rotor, or guide wheel, respectively.
In many technological processes conducted at high temperatures and pressures, e.g. in the addition of hydrogen to various reactants, one obtains mixtures of initially gaseous components from which the reaction products are separated after lowering of pressure and temperature. Examples for such processes are the ammonia synthesis, methanol synthesis and the hydration of carbon or oil fractions having a high boiling point for obtaining gasoline and other hydrocarbons required as intermediate products by the chemical industry. In these processes, the remaining residual gas, for instance hydrogen, which has to be present in excess for the reaction, usually has to be reheated, compressed and returned to the reaction vessel. These processes therefore require a high expenditure of mechanical (electric) energy for compression and recirculation of the gaseous components.
This energy expenditure can be reversed into an output of mechanical (electric) energy by combining the technological process with a thermodynamic process, wherein the gas leaving the reactor under high pressure and temperature is expanded in a power generating machine. Power generating machines of conventional construction are unsuitable for this purpose, however, since they attain acceptable degrees of efficiency only at very high volume flows and the flow paths in the rotor are not constructed for radial-axial deflection permitting concentration and selective separation of concensing mixture components. In contrast thereto, a fluid-flow machine of the type described herein is able to combine the functions of a mechanical separation apparatus (centrifuge) and of a power generating machine in a single operation by operating as a centrifugal gas turbine. Primary separation of the flow components may occur for instance at the outer elbows of the flow channels in a centrifugal-flow rotor, with secondary separation taking place in the adjacent guide wheel, or it may occur in a guide wheel with radially outwardly directed flow, with the secondary separation then taking place in the adjacent centripetal-flow rotor disc.
If the reaction products are composed of fractions having different boiling ranges, the separation of these fractions from one another usually requires an expensive distillation plant. The invention permits to do at least partially without this plant and to conduct a mechanical fractioned distillation already within a centrifugal gas turbine if the major portion of the product centrifuged at one stage is fed to an exteriorly heated evaporator by means of a pump, and the resulting steam is returned to the main gas flow at a higher pressure and temperature region. This recirculation increases not only the concentration of the products, but also the output of mechanical energy.
An introduction of flow components may also be provided in powered working machines--suitably at the elbow immediately downstream of the intake opening--in order to obtain an intimate mixture along the further flow path. In this manner it is possible for instance to inject water into a gas to utilize its vaporization heat for cooling the compressor.